Thanks! I was able to open the .tga files for editing. However, this leads to more questions...

How would you edit the snowtrooper (snowtrooper2.tga)? I could just paint it over with red... but a solid red would look bad, compared to the weathered look it has now. There must be some trick to it, because I have seen some spectacular edited skins...

Secondly, how would you change the skin of a unit in a map that your making, without changing it for the whole game? I want to change all of the clonetroopers (except pilot and jet trooper) on a certain map of mine to the regular white armor (rep_inf_trooper.tga).